Engine fuel system



Dec. 4, 1956 H. F. BUDZIEN 2,772,855

ENGINE FUEL SYSTEM Filed June 15, 1953 2v Sheets-Sheet l Dec. 4, 1956 H. F. BuDzn-:IN 2,772,865

ENGINE FUEL SYSTEM Filed June 15, 1953 2 Sheets-Sheet 2 ENGINE FUEL sYsrEM inigei E. `limizie, Beloit, wis., assigner to Fairbanks', lMorse a` Co.,` Chicago, lll., a corporation of Illinois `Application June 1 5, 1953, serial No. 361,707

` 4 claims. (o1. 26523) This invention relates to improvements in fuel systems for internal combustion engines, and more particularly to an improved fuel system for gasoline engines,'pr'ov idingautomatic regulation of engine fueliugfand effecting improved fuel admission to the engine.

The instant invention represents an improvement upon the engine fuel system described and claimed inmy `coperiding application Serial No. 270,080, led February 5`, 1952'.

"In portable and other internal combustion engine power plants `wherein the engine affording the power source, is cranked and started by a smaller cranking internal combustion engine, it is important that the cranking engine be adapted for positive and quick starting, and

for positiveand rapid power output response to varia-v tionsin cranking and starting conditions imposed by the larger engine." Accordingly, the principal object of the present invention is to provide for such crankingengines, an improved fuel system, including adjustable, automatically actuated fuel control provisionsiwhich is full'yfoperative to assure attainment of the aforementioned cranking engine operating characteristics.

vAnother object is to provide for cranking engines and particularly suchan engine having more than one cylin-` der, an air supply manifold common to the4 cylinders and havingfan atmospheric air intake conduit communicating 'with the manifold at a point thereof intermediate its length, an air throttle valve in the intake conduit, liquid fuel admission means individual to the engine cylinders and located relatively near the cylinder intake ports, and automatic control means in conjoint control control means for the throttle valve and fuel admission means is responsive inthe engine starting period when the'choke: valve may be partially or substantially closed,

to pressure variationsoccurring in the air intakefcon-Y duit anterior to or`on the atmospheric-air admissionfside of'the then partly or substantially closed choke valve.`

liA further importantV object of this invention is the provisionhof` an engine fuel `System vembodying Vfuel con# trol means individual to the engine cylinders and an airdelivery andcontrol means common to all cylinders, wherein the several fuel control means and the air control means vareeifective in response to variations of air pressure in the atmospheric air intake to the manifold, for regulating the admission of fuel and air tothe cylinders for determining the volumetric proportioning of these constituents, whereby to automatically adjust the Patented Dec. 4, 1956 2 eifective fuel mixture inaccordance `withvariations in engine'sp'eed and loading. t i f Another vobject of this invention isV to provide an engine fuel system controlled by a diaphragm means moyable in response toA changes in air pressurein the atmospheric air intake to the cylinder air supply manifold, and including an adjustable lspring mechanism for controlling the action of the pressure movable diaphragm` means such. as to determine and maintain anydesii'ed constant speed operation Aof the engine.

' Another object of the. present inventionV is to provide e ICC a fuel system for a multi-cylinder internal combustion engine, wherein air and liquidV fuel in atomized condi-` tion are mixed in a venturi and mixingzonev relativelycloselyadjacent each cylinder intake port, with the liquid4 fuel admitted through a fuel metering valve axiallyV aligned the `bore of the venturi anddischarging into the air stream at the throat, i. e., point of greatest con'- striction, of the venturi.

"Afurther object of the invention is `toi provide VanVen-,

gine fuel s yst'eri'il of theicharacter indicated, wherein a single diaphragm device simultaneously controls thefuel and air admitting means for the engine in response to variationsin the airpressure within the atmospheric air intake to the air supply manifold. l

It is a further object ,of he invention to provide an ,Fig. 2 is a sideelevation view of the engine fuel systems Fig.f3 is a section'view, with parts broken away, taken on line 3 3 of Fig. 1,-and showingin detail, one half of the essentially symmetrical apparatus; andV Fig. 4 isa sectional view with parts removed, on line 4-4 of Fig. 3.

. Generally speaking, the fuel system of the present intaken vention embodies a fuel nozzle and metering valve device individual to each cylinder and `disposed relatively closely adjacent the intake port thereof, an air supply conduit means including an air inlet portion containing an air, throttle valve whichA simultaneously controlsthe admission of air to all cylinders, and a flexible diaphragm device having a control member movable in response to pressure variations occurring in the air inlet portion of the cylinder air supply conduit means onthe atmosphericair intake side ofthe air` throttle valve. The fuel spring being so connected inlthe linkage as .to imposer valves, controlmember of the diaphragm device and air throttle valve are normally connected together by an to predetermined positioningof the `hand regulator, said i 7 a control-biasY upon the diaphragm. For any given set-v ting of the hand regulator to determine the speed at which the engine will run,the.` spring will exert acorresponding predetermined force on. the diaphragm Vin.

one direction, while the pressure within the air-*intake to the conduit means or manifold tends to move the diaphragm in the other direction. Hence, fuel mixture delivery to the cylinders is regulated in response to pressure variations in the air intake to the manifold to an^ extent determined by the governor spring tension, whichin turn'is determined by the hand regulator setting for controlling the speed of operationoftheengine. o To facilitate the use of Ya singleA diaphragm control device aslherein contemplated and to permit its adapta# tion forfeffective operation to, properly adjust and, control Vthe fuel and air valves in a manner toy determine eicient and proper fuel mixture indelivery toV the engine cylinders, the diaphragm control is `here made responsive to air pressure conditions closely representative ofthe operating conditions of the engine, occurring ata point in the air supply conduit system wherein the pressure and variations therein reect the average or mean manifold Vsuction pressures in engine operation.

T husthe diaphragmfcontrol may befthereby advantations. Hence, subjecting the diaphragm control device Vto such pressures anterior to the air throttle valve, results 4 l tion. Thus, the control device is thereby removed from direct response to the indicated heavy suction pressures obtaining in engine starting with the choke valve closed.

The fuel system is shown and described as applied to a two cylinder, cranking gasoline engine having its cylinders substantially in axially opposed relation, and wherein the cylinder fuel intake ports are spaced apart an appreciable distance. With such arrangement of the cylinders, the ordinary carburetor in which air and gasoline are mixed prior to delivery to a common intake manifold, has been found to begenerally" unsatisfactory for t-he purpose of assuringrcylinder delivery of proper in an improved stability of diaphragm function such as4 to assure attainment of` proper fuel mixtures in delivery tofthe engine over its entire operating range.

Particularizing further on theiforegoing and with rre-l gard to the normal inclusion of a choke valve in the air supply system, as to facilitate engine starting particularly underadverse or cold weather conditions, the present invention while providing for control response of o the diaphragm device to the pressure conditions obtaining. Y in the manifold airintake' anterior to or on the air. inlet side of the air control or throttle valve, affords.an .ade

vantageous operative relationship between the diaphragm` control and the choke Yvalve for assuring stableoperation of the diaphragm device during engine starting when 'the choke valve is ,partially or substantially closed. The

diaphragm control device as herein provided, isV adapted to have an operating sensitivity under the bias` ofthe governor spring within the range of adjustment of the latter, suflicie'nt, for nor-mal -relatively quick-action. respouse Yto pressure variations in the air intake anterior to the air Vthrottle valve, occurring during engine run.- ning usually with the choke valve thenin full-open posi,- tion. With the choke valve-located in the manifoldY air intake anterior Vto the air throttle valve, and actuated to apartially o r fully closed position, for engine starting, heavy suction-pressures occur inthe air manifold and in the air intake thereof posterior to the closed choke valve during cranking andY starting of the engine. Therefore, were the diaphragm ,device in pressure-responsive communication with themanifold air intake at any point thereof between theair throttle valve and the thenl closed choke valve,V the heavy suction pressures wouldtend 'to' and in fact, cause actuation of thedevice toward the extreme of its controlra-iige producing closure ofthe` fuel and air-throttle valves. Then, with closure of 'the Aair throttle valve, the resulting Adroppin the pressure 'be-d tweenthe throttle andY choke valves would cause an `oppositeilresponse of the diaphragm device, as 'to effect 'Y reopeningofthe fuel and air throttle lvalves.' 4"The 'ref sulting restoration of. heavy suction' Vpressure onf' the diaphragm, would Ythen cause the latter to repeat closure` ofthe fuel vland air throttle valves, and thereupon a-reopening of these valves Vin. the cycleV indicated. Con-V sequently, the-diaphragm control would undergo acyclic orV hunting operation. YInV order to avoid *thisl result, the diaphragm control device is arranged in suction-pressuref cor'nmunication with Ythe manifold `air intake ata pointthereinl which will lbe on the atmospherieair inlet side of the choke valve when the latter is in closed posifuel mixture necessary for positive and quick starting of cranking engines as herein contemplated. Hence, the fuel vsystem which forms the subject matter of this application, is .particularly useful in cranking engines and the like where the cylinders are-arraugd Suchthat the intake ports are spaced apart an appreciable-distance, but is by no means limitedto such'engines. In the drawings, the engine fuelingsystem includes an air intake generally designated 10, comprised of an atmospheric air intake conduit 11 providing a ,val-ve chamber 12, an air supply conduit or `manifold 14and.y fuel valve assemblies 16 arranged atV leach end Vv of theA air manifold 14. As best seen' in Figs. 2 and 3, co1,1d, uit'` 11 is located intermediate the length of manifold 14 preferably atrthe mid-point thereof, and is connected to the manifold as by means of machine screws 18,.suchY that the chamber 12 communicates'with the interior of the manifold. v

The fuel valve assemblies lare substantially identical,

Y although ,adapted for right and4 left hand application as Y' 14 is in communication with each venturi 22,wwhile1thelower end 26 of the passage 23 kopensvinto an intakeport 28 formed in the cylinderblock` 3 0.of theengine. l111-.` take valve 32j is mounted within thecylinder block, and, is engine-operated (not shown) for engineftimed `admission of-the fuel mixture into the associated; cylinder.

It will benoted thatfuel valveassemblies V16 aredisposedimmediately above theA inlet poppetyalves` of the engine Thus theirfucl andY air will bemixedin venturi 22 and passage 23, andv will pass, directlytothe cylinder Without having to.traverse any appreciable. distance. By this arrangement the fuel mixture is delivered tofthe` cylinder in an intimately mixed condition, with deliveryV effected directly to` the intake A'port ,28 .from the shorty lengthmixing chamber-'or passage23 vso that theatomized anclvaporizfed gasoline has no appreciable opportunity to precipitate or separate from Vthe mixture. This, of.4 course, facilitates the attainment vof moreA perfect com# bustion inthe cylinders, and-{representsalfeatureofl-this- Y invention. i

air throttle' :valve 34: is,v mountedwithin-*the ilower' partfof; chamber 172,yand a' choke valve l'ismountedin. the, upperipart kofgthe chamber. `The throttlevalveis pivotally-'mountedzby means- Ofvshaft, andthe choke valvevis pivotally mountedV by meansofi the,- shaftV 40. Both ofthese valves. may beyof thevbutterllytype, and are. shown in Fig, -Sin their,wideopenfpositions. .011e` end Off Shaft 33extendszbeyond the wall..,of charnf ber 12 agallas Secured'thetet a fcrankarm 42,.wl1ile thev opposite end of shafttl extends beyondthe 'chamber'- and carries another vcranlmrnfl4a. A ballheadlnin 46, (Fig- 4`),.is carried on one Side at the. freeendofgcrauk 42- anda 'ballhead pin 48` is carried on the other" side thereof. A ballhead pin 50 is carried on the free end of crank 44. Referring to Figs. l and 2, it will be seen that atie rod 54 is connected with crank 42 byimeans of a socket 56 cooperating with ballhead 48. Another tie rod 58 is connected-to crank 42 by means of a socket 60 fitted over ballhead 46. The rod 54 is operatively connected to the fuel metering valve in the right hand valve assembly 16, while tie rod 58 is connected with the fuel metering -valve in thev left hand v-alve assembly, as well as with a diaphragm control mechanism now 4tobe explained.

Chamber 12 of the air intake conduit 11 has a disc `shaped portion 62 formed integral therewith. A circular A plate 64 is secured to portion 62 by means of machine screws 70, these screws also securing the diaphragm margin in sealed condition between the members 62 and64. The right hand sideV of cavity 68 (Fig. 3) communicates with the interior of chamber 12 in the zone of choke valve 36, by means of a passage 72, while the left hand side of the chamber communicates with the atmosphere through a suitable relief port 73. As may be observed in Fig. 3, the passage 72 communicating the diphragm control device withthe manifold air intake conduit `11, opens into the chamber or passage 12 of the conduit at a point therein which while definitely anterior to the throttle valve 34, is also anterior or on the air inlet side of the choke valve '86 when *the latter is closed.V Thus, the diaphragm-is subjected to atmospheric pressure on one side, and on theV other side Vto the pressure in the air intake chamber 12 `ahead of or anterior to the throttle valve 34A during engine operation and ahead of the Vchoke valve when closed in engine starting. As before noted and as will be hereinafter pointed out, certain important advantages stem -from subjecting the, control diaphragm to theair pressure conditions obtaining in the indicatedregion of the conduit 11, i

A rod 74 is secured tothe diaphragm in a conventional manner so as to slide within a boss 76 formed on platev64. Rod 74 is bifurcated as indicatedAiat 78, to` receive a lever 80 which is pivotally mounted within the bifurcated end of the rodby a pin 8,' 2 (Figgl). Oneend of lever 80 is `connectedto tie rod 58 by means of a ball and socket 84,` and the same endY of Vthe lever is connected to tie rod 86 by means of aball and socket connection 88.; j .i The other end of lever 80 is pivotally connected byJ pin 92, to a link 90 supported by plate`64.` With this arrangement the position of the diaphragm and its push rod and, consequently, the position of lever 80,'vwill be dependent upon the pressure-differential between'atmospheric pres'- sure on one side of thediaphragm andthe pressure on the opposite side of the diaphragm consequent to the presatrasos Correspondingly,l when stem 104 is threaded outl of bore 102, the valve is opened. v i An important feature of this invention `"resides 'in the relative positioning of valve 20 andveturi 225v As best -see Vin Fig. `3, theb'ody member 94 has-a 1`ioz'zle105 extending from valve seat 98 to the throatv of venturi 22, which nozzle is pvided With-a fuel passage 107. f' Thus fuel will flow between needle valve 106 and valve seat 98, through passage 107, and be discharged from nozzle-105 substantially axially into the throat of venturi'22. VDue'to the restriction of the venturi, a high air yelocity-existsfat the throat thereof, and liquid fuel will bethereby vwithdrawn from nozzle 1075 by atomizer action, to completely vaporize-the liquid fuel and thoroughly mix thefvap'or and air. W :I It is particularly important tonote that the nozzle 105 is axially aligned with the venturi; With this arrangement the air iiow through thefventuri is' notunduly impeded,

because of the smooth ow lines offered by nozzle 105 and the sides `of `venturi 2v2.l Furthermore, it has been found thatwith this'farrangement, erratic turbulence is avoided lin` the 'air flow through the venturi, so that homogeneous fuel mixtures are attained such as to facilitate highly efficient fuel combustion in the engine cylinders. i A lever 108 is mounted for free rotation on the upper end of stem 104, and a notched wheel or indexing knob 110 is secured to the upper end of the'stem above lever 108. Lever 108 carries a 'spring clip V112 (Figs. 1 and 2), which releasablyI engages notched wheel 110. At the end of lever 5108 opposite spring'clip -112, "a ball and socket connection 114 secures the lever to theassociate'd one of saidtie rods 54and 86. i j A Spring clips 112 normally connect levers 108"to"th,e valve stems 104.- Thus, when tie rodsi54'and'86are moved to the right `as 'viewed'in' Fig.` l, the'rightx hand and lefthand needle valves will be `moved, towardclosed position, and when these tie rods are `moved to the left, the valves will be moved in the valve opening direction. In order that the needle valves may be adjusted independently of the linkage system',whichincludestierods554'and 86, spring1clips112 may be manuallydisengaged from the notched wheels 108-an`d the valve stem rotated Aby hand. By this adjustment',fthe,fuel valveslrnay be set in corresponding positions. f t" l. "li "1 lFromthe foregoing description it should beV evident that the-positioning `of throttle` valve 34 and fuel valvesf20 is, m normaloperation, `under` control ofthe pressure Iinthe air intake conduit as it influences'the positioning v.of

diaphragm 66. That is, if the pressureiwithin" air valve sure condition obtaining in air intake conduit 1.1 anterior f to the air throttlevalve34 therein, with diaphragm re` sponse to such pressure-differential regulated by a suitable governing spring as hereinafter described. Movement of lever 80 will cause throttle valve 34 to be operated through i tie rod 58 and crank 42. As will be hereinafter explained, mqvementvoflink'80 ".will also cause the fuelyalvesfto beoperated. Y L 'v "As, best seen in Fig. 3,. fuel valve'2 0 is a needle valve `which' controls the admissionlofffuel tothethroat'of venturi 22. Valve 20 includesa body member f94'mounted in. a housing 95 by means of machinescrews'96 (Figs. y

chamber 12 decreases, the `rod 74 connected ywith diaphragm `66 is moved into plate 64 so as'tol move tie rods `54, 58, and 86 in a direction to close fuel valves 20 and to close` throttle valve 34. Likewise, if theipres'sure `increases, thediaphragm causes valve actuationin theopen@ ing direction. v i' important featureof this invention is the provision of an automatic lspeed governing controlforthe engine. A governing` spring1-16 is connected between lever v80 and a hand;control 118. Control 118 has a winged head 120, and. a;threaded shank l122,V which is threadedly4 re' ceived within a control mountingplate 124. Anut 1264 is threaded over shank.,122landdisposed onithe forward side ofplate124, while'another nut `128,-'carried by shank servesltoilimit theextent, that hand. `control 118"may.sbel

threaded outof` plate.V 124 so as to` lirnitthe maximum amount of tension that may be created -within governing spring 116. Thus, the `disposition of nut 128 controls-the idling position of the airand fuel valves. lNut12,6 serves to limit the extent that the Ahand control may be threaded into platfei`124, and thereby serves `asia stop when` the engine is at full throttle. Y l

v Gasolineis supplied to fuel valves 20 from a tank 130 through tubes 132 (Figs. land 2). The fuel tank is disposed below the manifold 14 oncylnder block 30 of the engine. With this arrangementgfuel yllows to thefuel valves unitn/.henVV a fvacuum' condition :exists adjacent .nozzle- 105; within each venturi 22, andv therefore the engine; can not'becomefooded when it is not in operation.

Asbest seen ilIaPig. 1, a .choke lever 13.4' is slidably mounted within control mounting plate 12'4, and has one end connected ,to ballhead50 .of crank 44', -as through a socket 136. The butterfly choke valve 36 may' be closed or.,-partiallyg.closed, -as at starting` particularly in cold .weather,to, provide al rich .fuel mixture for the engine, by pulling the choke'lever tothe left. as viewedin Figs.l 1 and 2.. .During` normal operation, 'the choke .valve r3,6 will, ofcourse, be maintainediina wide open position,.i. e.,

e the position shown in Fig. 3.

Describing nowtheoperation of the `fuel syst-em, it should befappreciat'ed that whenthe; engine is not running, only the force` of spring -1-116wil1 be,` .exerted on theflinkage system, so ,that the ivalves will all ybe open since no reducedpressure-then existsin the intake conduit ofthe manifold to oppose thev spring force. `In starting `the engine, the handcontrolv 118 ispositionedrelative toplate 124, lsuch Vals to determine spring-.loading of the fuel .control system sayfor anengine-idling condition. Withfthe hand controlso disposed, the choke lever 134 may be operated' to close choke4 valve 36 and the engine cranked or turned over ingany convenient .manner to start -the engine. Since the passageg72is open to chamber 12' on the air inlet side lof thenow closed choke valve 36, the diaphragm control ,will respond to the air-pressure conditions obtaining ahead ofthe choke valve, such `as f to establish and maintain the spring-set idling condition of engine fueling once the engine starts upon cranking. .'lhusthe control is removed from the heavy suction pressures posterior to the closed; choke valve as hereinbefore explained, wherebyv toV avoid the disadvantageous effectsV including hunting operation of the control as before described As soon as the vengine ,is in operation, the choke fis gradually. released untill the Vengine runs evenly, and the hand control1-18 then may-be set to run the engine' atV the Vdesired or required cranking speed; -Since the right handyside of the diaphragm-.chamber 68 (fFig`.-' 3) fcommunicates with the air valve chamber :12 at'the point ndicated, the diaphragm 66 will'be subjected to-V the vpressure .condition in the portioni of. the air'inlet chamber 12 anterior-to the air throttle va1ve"34,-resulting ina pressure? ditferentialion thefdiaphragm tending to cause 'diaphragm movement to 2the'. right'as viewed'in Fig. 3against the bias ofy governor spring v116. Thus under steady state operating conditions, the Vdiaphragm 66 ywill assume a position such. that'the force exerted by the' pressure dif- Vferentialexisting between-opposite sides of the diaphragm,

diaphragm 66 will assume a position in response thereto, suchv that the forces acting on the diaphragm will be in balance. Thus, with the engine running at a given speed determined by the setting of the hand control, if the engine loading is increased the speed will tend to decrease, with the result that the pressure in air intake conduit 11 eiective on the diaphragm 66, then will change correspondinglyy and such as to permitV the governor spring 116 to cause diaphragm retraction and-,consequent movementof lever 80 clockwise as viewed in Fig. l, to effect further opening of the fuel .andair valves. The resultant increased fuel mixture delivery then will cause the engine to resume its former speed of operation. If.` the engine is operating ata given speed and the load is removed or reduced so that the speed tends to increase, the pressure within housing 12 changes in the opposite sense, thereby to cause movement of lever 80 in a counterclockwise direction as viewed in Fig. 1. This movement of lever 80 produces actuation of fuel valves 20 and throttle valve 34' to reduce the quantity of fuel mixture supplied. to the engine. Thus, under the new load condition, the engine re-assumes the constant speed of operation as set by the hand control 118. It should be appreciated that the above mentioned governing action is very quick in response to speed changes, and while the governing action has been described as a step by step process, for all practical purposes the steps are substantially simultaneous.. u n

' .For eticient operation of an-internal combustion engine andparticularly the cranking engine hereincontemplated, it Vis'ir'nportant that the fuel mixture be varied only in accordance with the requirementsof the engine under different -speed and load conditions. By subjecting diaphragm 66 to the pressure within valve housing 12 ahead ofthe air throttle valve and near the air intake port 75 of the conduit 11, the diaphragm will be subjected to a `relativelygconstantv force for a given engineuspeed. In

`other words, the pressure in housing 12 is substantially fold such as in venturis 22, is fluctuating. The lluctuaf isnequalto. theforce exerted on the diaphragm by. gov- A erning spring 116. Y Y Y Y Assuming the engine is running lat'a constant speed with the .hand controlset a' t-itsffull engine speed position,V the diaphragmr66 Ywill-{aussrume-a position in the left hand side: ofdiaphragm ichainber68 as viewed in Fig. v3. Thus tic; rodsf54, and 86 =will be-'moved byleuer 8.0 jto positions S'opening air'throttle valve 34 andV fuel valves 20;;to1'amaximum amuntfthe amountwhichl the fuel Vvalves are openedv being,dependent upon v,the,relative positions of engagement-3 between spring clips "1'1`2`V of Y leversf'108-and notchedV wheels'110. VIVE-fthe engine "operatedat alsteady idling speed vor any other slow'spfeed 1 as-determinedfbyfthefsettingofhandf control 118 theV diaphragmV will'i bedispose'cl'in the right hand side ofchamberesas-viewed in Figs." 1, v2, and 3. VInthisposition, the diaphragm will have moved'tierods 54,58, and

`86 solthat fuel'valves 20 andair throttle yvalve 34 arelin relatively closed ,positions u u ,Describing-y now the governing Vaction .ofthe fuel'system Yupon a changeinpressure in the air intake` conduit. of

manifold* '1'4 vand'anterior' to" air. valve 34 therein, the

tion of pressure in theventuris .and in the manifold 14 is caused by theintermittant -opening `and closingv of poppet valves 32:; When the poppet valve. is open and a fuel mixture is being drawn into the cylinder, aiicertain pressure exists in'V the venturi associated therewith, and when the poppet-valvejis closed, lthe Ipressure` in the venturiwill be `of`a different magnitude; The two cylinderlengine shown in thedrawings'may operate'so that the poppet valve associated with'.V the Vleft hand cylinder is open when theV poppet .valveassociated' withthe right hand cylinder is closed, andfvice-versa, so that the pressure in the venturis may `be' instantaneously different However, the pressurereflected in housing 12 anterior-to theair valve 34. will be of` a relatively Aconstant magnitude for a, given engine speed, and the force exerted by the pressure ditferentialacross the diaphragmA 66 then. will be substantially constant. Hence, only an actual change in speed'of operation. of the engine as produced by load changef'ofr change in other operating conditions, will cause suicient unbalaneV of .forces on the diaphragm to changethesettiugs "'o'f'the ffueland air valves; Conse-v Y' to provide an efhcient fuel. mixture. and constant Aspeed operation. The fuel system also assures delivery- 'ofa proper fueland air' mixture 'to '.thecylinders, since'the mixingiof thefuel constituents is effected in the chamber Y relatively 'close to the intake passageof the cylinder, by the novel arrangementof the fuel Valve and venturi.

Furthermore, the system is relatively simple and the working parts, including the pressure actuated diaphragm, are not subjected to unnecessary adjustment by pressure uctuations.

The foregoing specification contains a complete description of one form of my invention as required by 35 USC 112, but it should be appreciated that various changes, modifications, and permutations may be effected without departing from the scope of the appended claims.

I claim:

l. In a fuel system for a multi-cylinder engine having an inlet port for each cylinder, an air intake manifold including an air intake passage in communication with the atmosphere and having spaced openings in communication with said inlet ports, fuel valves disposed adjacent said inlet ports, a throttle valve for said air intake passage of said manifold, a linkage connecting said valves for conjoint operation, a member connected to said linkage and exerting a biasing force thereon in a direction to open said valves, a diaphragmconnected to said linkage and subjected to the pressure in said air intake passage on the intake side of said throttle valve, normally effective to exert aV force on said linkage system in a direction to closed said valves, and means to vary the amount of biasing force applied to said`linkage by said member.

2. In a fuel system for an internal combustion engine providing at least two cylinders each having a fuel inlet, means adjacent the fuel inlet of each cylinder providing a fuel and air mixing chamber, means including a fuel valve at each mixing chamber for the admission of fuel thereto, an air supply conduit common to said mixing chambers and having an air inlet portion intermediate the conduit length, an air throttle valve in said inlet portion, a choke valve in the inlet portion anterior to the throttle valve therein, linkage means interconnecting said fuel valves and air throttle valve for conjoint actuation, adjustable spring means connected to said linkage means and effective therethrough to bias said fuel and air 'throttle valves to open positions, and a control device responsive to air pressure in said inlet portion of the air supply conduit at a point therein which is anterior to the choke valve in the closed position of the latter, said control device being connected to said linkage means and effective therethrough in opposition to said spring means, to determine control positions of the air throttle valve and fuel valves in accordance with variations in the air pressure at said point in the conduit air inlet portion.

3. In a fuel control system for an internal combustion engine providing at least two cylinders each having a fuel inlet, means adjacent the fuel inlet of each cylinder providing a fuel and air mixing chamber, fuel admission means including a fuel control valve for each mixing chamber, an air supply conduit common to the mixing chambers and having an air inlet portion, an air throttle valve in said inlet portion, a choke valve in the inlet portion anterior to the throttle valve, linkage means interconnecting said air throttle and fuel control valves for conjoint actuation, a spring connected at one end to said linkage means, means supporting the other end of the spring, said spring acting through said linkage means tending to dispose said vair throttle and fuel control valve in open positions, and a pressure operated device responsive to lair pressure in said inlet portion at a point therein which is anterior to the choke valve in the closed position `of the latter, said device being connected to said linkage means and effective therethrough in opposition to said spring, to determine control positions of the air throttle and fuel control valves in accordance with variations in the air pressure at said point in the conduit air inlet portion.

4. In a speed-settable, constant speed internal combustion engine, having at least two cylinders each having a fuel inlet, a fule system therefor comprising meansV adjacent each cylinder fuel inlet forming a fuel and air mixing chamber, fuel admission means for each mixing chamber including a fuel valve, an air supply conduit common to said mixing chambers and having an air inlet portion, an air throttle valve in said inlet portion, linkage means interconnecting said 4air throttle valve and fuel valves for conjoint actuation, a pressure operated device yconnected to said linkage means and operable in response to air pressure Variations in said inlet portion anterior to the air throttle valve therein, for actuating said air throttle and fuel valves, a tension spring connected to said linkage means and effective therethrough in opposition to said pressure operated device, to bias said air throttle and fuel valves toward full open positions thereof and to determine the extent of pressure responsive operation of said pressure operated device, and means for adjusting the tension of said spring whereby to alter the extent of pressure responsive operation of said pressure operated device. f

' References Cited in the le of this patent UNITED STATES PATENTS 1,901,849 Moore Mar. 14, 1933 2,134,889 Phillips Nov. l, 1938V 2,293,842 Mallory Aug. 25, 1942 2,428,377 Morris Oct. 7, 1947 2,562,656 Blakeslee July 31, 1951 2,595,720 Snyder May 6, 1952 2,595,721 Snyder May 6, 1952 FOREIGN PATENTS 556,726 France Apr. 19, 1923 

